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Created attachment 13193[details]
hangcallstack
Originally raised on the forum by Andrew Arnott:
http://forums.xamarin.com/discussion/52746/xamarin-android-hangs-vs-for-long-periods
When installing a NuGet package to a new Xamarin.Android project, VS hung for several minutes. I broke into VS with the debugger and found via the callstack (attached) that the hang is caused by the NuGet package manager enumerating references, causing the C# project system to request a synchronous design-time build on the UI thread, leading to MSBuild running a Xamarin.Android task. The Xamarin.Android task downloads many megabytes of data from the Internet. This seems very inappropriate for a design-time build, which is supposed to run in under 200ms. Please adjust your Xamarin.Android MSBuild targets to skip expensive tasks like this during design-time builds!

I'm able to reproduce this on the current stable as well as active Cycle 6 builds. I'm not entirely sure how much of an impact clearing the NuGet/Xamarin package caches has on this, however attempting to add GooglePlayServices - All from a clean state is certainly quite painful.
Steps to reproduce:
1. Delete the following cache locations if they exist:
> %LOCALAPPDATA%\NuGet\Cache
> %LOCALAPPDATA%\Xamarin\Android.Support.*
> %LOCALAPPDATA%\Xamarin\GooglePlayServices.*
2. Create a new hello world android template
3. Right click on the project/solution -> Manage NuGet Packages...
4. Search for "Google Play Services All", select and install that option once it appears.
With this workflow, you can see VS free up _briefly_ in between package additions. However if you're attempting to add 5+ packages or so (quite noticeable when adding all of the google play services packages), this results in a few minutes of unresponsiveness.